The Goldilocks Asahi-Pentax and later, modern take, Pentax 67 bodies are very difficult repair jobs. Inside these behemoths is a lot like a watch and just as tiny. A heavy drop will dislodge, unlink or misalign all the business in there and it is very, very time consuming to track it down, which is why so many repair shops say they have fixed it but yet lack the tenacity to go really deep down, irrespective of the cost of doing so. The shutter dial speeds are controlled by resistors. It's a known fact that keeping the shutter cocked for an extended period of time will make shutter speeds inaccurate.
You would be paying a fortune for labour, not parts: inside are lengths of wire, resistors, a solitary capacitor, hundreds of springs, pawls, clips, cogs, gears and pulleys — all harking back to literally the horse and buggy era! The only concession to modern electronics is the little red LED on the top cover. The shutter and mriror operate by way of solenoids and magnets exchanging power through a rudimentary circuit of contacts all coming back to the the shutter speed dial. Mirror and shutter magnets will expectedly 'lose their grip', so to speak, over many years and thousands and thousands of exposures (there is a very vulnerable and known problematic magnet directly under the shutter button that often required deguassing). There are no integrated circuits or fancy electronics, just good old clockwork on a small and complex scale (a good reason why it's not DIY ). Pentax itself does not offer a repair service for any 67 bodies partly because such a repair would most likely well exceed the cost of the camera itself, but also that no spare parts in back inventory are available — they would have to be cannabalised from another 67 body. So... a 67 body playing up will essentially have to remain like that until you come across another as a replacement. It's all very gloomy and it's what I keep in mind with my own: the reality is these cameras are now very old and many, many will require repair quite extensive repairs at some stage.